Various methods and systems for construction of three dimensional models or objects have been developed for a number of applications, including the rapid fabrication of prototypes and the low volume fabrication of models and objects of varying degrees of complexity.
The need for rapid, low cost, low volume fabrication of models and parts has generally been met by various three dimensional (3D) modeling processes that employ layer by layer building processes. According to typical prior art three dimensional modeling processes, a model or a part is built up by the successive deposition of layers generally comprising a “model” material forming the final part to be manufactured and a sacrificial material that provides support for the model material during the building or fabrication process. Following completion of the fabrication or building process, the sacrificial material is subsequently removed thereby leaving the model material which forms the final part to be manufactured.
Typical examples of three dimensional modeling processes of the prior art include, for example, Householder, U.S. Pat. No. 4,247,508, which describes a modeling process that employs two substances, one a fill material and the other a mold material, that are deposited layer by layer to build an article. The two materials in each layer are not in contact with each other while the layer is being formed because Householder '508 uses a grid to separate the two materials as they are being deposited. After the materials in each layer are deposited, the grid is moved to the next layer so that the two materials may fill the space left by the removed grid and thereafter solidify in contact with each other in the same layer.
Helinski, U.S. Pat. No. 5,136,515, describes a method wherein a three dimensional model is produced layer by layer by jetting droplets of at least two solidifiable materials, one material forming the article and a second material forming a support for the article. The second material is subsequently removed by heating, cutting, melting, chemical reacting, and so on, to leave the desired article.
Penn, U.S. Pat. No. 5,260,009, describes a system and process for making three dimensional objects by dispensing layer upon layer of modeling material using an inkjet which is turned “on” or “off” according to a two dimensional data map of each layer of the object. The two dimensional data map is stored and relayed by a microprocessor and defines locations on a matrix at which printing is to occur in a manner such as is used in printing images using raster scan printing.
Sanders, Jr. et al., U.S. Pat. No. 5,506,607, describes a system for building three dimensional models by vector plotting layer-upon-layer applications of solidifiable substances. The layers are formed by expelling minuscule beads of the substances in a liquid or flowable phase onto a platform from one or more jets wherein the jets and platform are relatively movable in the X, Y and Z coordinate system and the beads are deposited along vectors during X-Y relative movement.
Sanders, Jr. et al., U.S. Pat. No. 5,740,051, describes a method and apparatus for producing a three dimensional model by forming a continuous plurality of parallel layers of modeling material by repeatedly producing a plurality of bead producing drops of the modeling material for deposition at desired locations, controlling the locations and timing of deposition to produce vectors in any and all directions required to produce an outer surface defining a wall of a layer with a desired surface finish, and adjusting the distance of the location of drop production to the location of drop deposition in preparation for the formation of a subsequent layer.
Penn et al., U.S. Pat. No. 6,175,422, describes a method and process for computer-controlled manufacture of three dimensional objects by dispensing a layer of a first insoluble material, such as a liquid, onto a platform at predetermined locations corresponding to a cross-section of the object, which then hardens. A second material, preferably water soluble, is then sprayed onto this layer to thereby encapsulate the hardened insoluble material. The uppermost surface of this encapsulant is planed, thus removing a portion of the encapsulant to expose the underlying insoluble material for a new pattern deposition. After the resulting planing residue is removed, another layer of liquid, insoluble material is dispensed onto the planed surface. The insoluble material can be of any color and may vary from layer to layer, and from location within a layer to location with a layer. These steps are repeated, until the desired three dimensional object, encapsulted in the soluble material, is completed. At this point, the object is either heated or immersed in solvent, thereby dissolving the soluble material and leaving the three dimensional object intact.
Other systems and methods of the prior are described, for example, in U.S. Patent Publication No. 2009/0252821 which relates to a method of fabricating a model by deposition of a model material and a sacrificial material in layers wherein the sacrificial material which defines the bounds of the model is deposited, drop by drop, and the model material is deposited at high speed by spraying, while U.S. Patent Publication No. 2010/0021638 additionally describes the use of a third material to construct the layers and U.S. Pat. No. 6,019,814 relates to the use of a nozzleless, ultrasonic device for the sequential deposition of the materials.
U.S. Patent Publication No. 2005/087897 relates to a variation of the basic method for constructing a model by deposition of successive layers of a model material comprising the model and shell material enclosing the model material wherein certain layers may be deposited as partial layers to reduce the volume of material to removed when each layer is planed and to permit the construction of more complex geometries in the layers.
U.S. Pat. No. 5,209,878 relates to the use of either thin partial layers of material or a material capable forming a meniscus in the edge regions between successive layers of different dimensions to reduce or eliminate “stairstep” voids created at the edges of layers having different dimensions.
U.S. Patent Publication No. 2002/0129485 describes a system which is an agglomeration of previously known systems for fabricating three dimensional objects which thereby provides a very flexible but complex system capable of achieving features of a wide variety of methods.
Other prior art systems employ methods somewhat analogous to those used to construct three dimensional objects as successive layers of different materials, but as adapted specifically and essentially to object molding processes. For example, U.S. Patent Publication No. 2004/0089980 describes a method for fabricating three dimensional models by deposition and machining of three or four successive thick layers, thereby concurrently forming a mold for the object and the object itself. The layers include including a first additive (non-sacrificial) layer which is machined to define the bottom contour of a next layer, which is a second additive (non-sacrificial) layer. The second additive (non-sacrificial) layer is deposited on the first subtractive (sacrificial) layer and machined to define the upper contour of the second additive (non-sacrificial) layer, which is the top of the finished model, with a second subtractive (sacrificial) layer being deposited and machined, if desired. The subtractive (sacrificial) material is removed when all layers are completed, thereby leaving a model formed of the additive (non-sacrificial) material.
U.S. Pat. No. 7,003,864 describes a method that is generally similar to that described in U.S. Patent Publication No. 2004/0089980 in depositing and machining three layers which concurrently form a mold for an object and the object itself, including depositing and planing a base layer of support material, depositing and removing regions of a second layer to form a mold of the part, adding a construction material to the removed regions of the second layer, and planing or machining the support and construction materials of the second layer.
The methods and systems of the prior art, for fabricating three dimensional models and objects, however, each have a significant number of fundamental problems.
For example, certain systems, such as those described in U.S. Patent Publication No. 2002/0129485, U.S. Patent Publication No. 2004/0089980, U.S. Pat. No. 7,003,864, fabricate objects or molds by machining the objects or molds from relatively thick layers of material. Such systems, however, require the removal of significant amounts of material by machining processes and tools that are capable of the desired precision and often require a variety of machining tools heads in order to obtain the desired contours in the objects or molds, so that such systems and are typically slow and wasteful and requiring complex, expensive machining components or elements.
Other of the systems and methods of the prior art, such as those described in U.S. Pat. No. 4,247,508, U.S. Pat. No. 5,136,515, U.S. Pat. No. 5,260,009, U.S. Pat. No. 5,506,607, U.S. Pat. No. 5,740,051, U.S. Pat. No. 6,175,422, U.S. Patent Publication No. 2009/0252821, U.S. Patent Publication No. 2005087897, U.S. Pat. No. 5,209,878, and U.S. Patent Publication No. 2002/0129485, fabricate objects by the deposition and selective removal of thin layers of two or more materials, thus allowing the fabrication of more complex objects by relatively less complex or expensive systems. Such systems, however, require that at least one material be deposited on the layers, during the building process, by a drop-by-drop deposition process in order to define the surfaces of the object with the desired precision but this results in a relatively slow building processes, thus increasing the time and cost to fabricate each object and reducing and either reducing the rate of production of objects or requiring the addition of further fabrication machines to achieve a given production rate.
Still other significant and persistent problems of the systems and method of the prior art include the establishment, monitoring and control of the positions, orientations and position and orientation tolerances of and between the elements of the apparatus for fabricating three dimensional models, including the thicknesses, rates of deposition and edge orientations and tolerances of the deposited materials.
The present invention provides a solution to these and related problems of the prior art.